Fig. 1. Different types of breathing behaviour occurred in resting Camponotus. (A-D) Various patterns of the discontinuous gas exchange cycle (DGC) in single decapitated minor worker ants. CO₂ is released supposedly via a single spiracle (A), via two spiracles as indicated by the arrows (B), or via three spiracles (C). Alternatively, a single spiracle might open repeatedly within one breathing cycle. (D) Time-expanded DGC. Large CO₂ spike represents tracheal opening phase. Small spikes of gradually increasing amplitude signify spiracle flutter phase. (E) DGC in an intact ant during rest. This breathing pattern is characterised by prolonged spiracle opening during flutter phase and no distinct opening phase. (F) Continuous breathing (or higher flutter frequency) behaviour in a decapitated minor. Continuous breathing mode was further observed in all ants during locomotion. C, closed phase, F, flutter phase and O, spiracle opening phase. Inset sketches illustrate decapitated and intact situations.